664320

Appears in sequences

• Numbers k such that phi(prime(k)-1) == 0 (mod k).at n=18A067733
• a(0) = 1; a(n) = Sum_{k=1..n} (-1)^(k+1)*d(k+1)*a(n-k), where d() is the number of divisors (A000005).at n=23A307241